PHYT 7103 Human Physiology Module 1

Study Notes

Cell Membrane: Composed of phospholipid molecules; regulates substance entry and exit.
Structure Impact on Transport: Features a glycerol hydrophilic head and hydrophobic fatty acid tails.
Cholesterol Role: Prevents tight packing in low temperatures and reduces leakiness in high temperatures.
Semipermeability: Allows passage of O2 and CO2 but blocks glucose and sugars.
Phospholipid Molecule: Contains hydrophilic head and hydrophobic tails; amphiphilic nature is essential for membrane formation.
Protein Channels: Facilitate selective transport through passive diffusion without energy expenditure.
Cytoskeleton: Provides structural stability through proteins like microfilaments and microtubules; enables cell shape changes.
Intracellular Fluid: Composed of cytosol; medium for cellular reactions.

Cell Membrane: Regulates substance exchange.
Nucleus: Houses genetic material (DNA and genes).
Ribosomes: Synthesize proteins using mRNA.
Endoplasmic Reticulum: Rough ER synthesizes proteins; Smooth ER produces lipids and steroid hormones.
Golgi Apparatus: Modifies and packages proteins/lipids from the ER for transport.
Transport Vesicles: Aid movement of materials within the cell.
Mitochondria: Produce energy (ATP) for the cell.

Definition: Maintenance of a stable internal environment critical for physiological functions.
Key Values: Blood glucose level at 90 mg/ml, body temperature at 98.4°F.
Steady State vs. Homeostasis: Steady state indicates constancy but does not imply homeostasis (e.g., during exercise).
Negative Feedback Components:
- Controlled Variable: Maintained within narrow limits.
- Set Point: Target value for control processes.
- Sensors: Monitor changes in controlled variables.
- Comparator: Identifies deviations and initiates responses.
- Effectors: Restore the controlled variable to its set point.
Intracellular vs. Extracellular Fluid:
- Intracellular Fluid (ICF): Fluid within cells.
- Extracellular Fluid (ECF): Fluid outside cells, subdivided into interstitial fluid and blood plasma.

Selective Permeability: Regulates which substances can enter or exit the cell.
Transport Mechanisms:
- Diffusion: Passive transport for small, nonpolar molecules (e.g., O2, CO2).
- Facilitated Diffusion: Utilizes transport proteins for larger, polar molecules.
- Osmosis: Movement of water across a semipermeable membrane from low to high solute concentration.
- Primary Active Transport: Uses ATP for sodium/potassium pump function.
- Secondary Active Transport: Utilizes electrochemical gradients without direct ATP use.
- Bulk Transport: Involves endocytosis (material uptake) and exocytosis (material expulsion).

Endocytosis: Engulfing extracellular materials into cells.
- Phagocytosis: Engulfment of debris and dead cells.
- Pinocytosis: Capture of extracellular fluid and solutes.
- Receptor-Mediated Endocytosis: Absorption of specific proteins/hormones.
Exocytosis: Expelling materials from cells.

Process: Responsible for maintaining cell shape by preventing swelling or shrinkage.
Tonicity Terms:
- Isotonic: Equal solute and water concentration.
- Hypotonic: Low solute, high water concentration (can cause cell swelling).
- Hypertonic: High solute, low water concentration (can cause cell shrinkage).

Adenosine Triphosphate (ATP): Energy currency of the cell, formed through glycolysis, Krebs cycle, and electron transport chain (ETC).
ATP-PC System: Provides energy for short bursts of activity (e.g., sprinting) by breaking down ATP and phosphocreatine.
Glycolysis: Anaerobic process breaking glucose into two pyruvate molecules, yielding two ATP; occurs in the cytoplasm.
Citric Acid Cycle (Krebs Cycle): Produces energy equivalents (GTP, NADH, FADH2) and generates ATP (30-32 ATP total).
Electron Transport Chain (ETC): Transfers electrons, creating a proton gradient to synthesize ATP.
Oxidative Phosphorylation: ATP production via electron donation from NADH and FADH2.
Aerobic Activity: Long-distance running and cycling predominantly utilize aerobic ATP production.
Nutrient Utilization: The body primarily uses carbohydrates for short-term energy and fats for prolonged exercise.